The SADD study ranked texting highest in the following list of behaviours which were all rated as "extremely" or "very" distracting for teens behind the wheel:

Instant or text messaging while driving - 37%

[The teen driver's] emotional state - 20%

Having several friends in the car - 19%

Talking on a cell phone - 14%

Eating or drinking - 7%

Texting while driving can have devastating consequences . It was only last month that 19-year-old Rachel Begg was sentenced to four years for dangerous driving after she killed the driver of the car she hit while texting.

Begg had used her mobile phone nine times during a 15-minute journey, a trip that saw her reach speeds of 70mph. Her victim, 64-year-old Maureen Waites, died at the crash scene.

Perhaps most tellingly, the study data also compares the potentially wayward teens with their parents. Almost two thirds (62 per cent) of those questioned had seen their parents use a cell phone while driving. SADD urges parents to drive as they say, not as they do.